农地边际化的表现特征及其诊断标准

本文对农地边际化与边际土地的概念与本质、农地边际化在区域土地利用中的表现特征及其诊断标准进行了理论探讨。农地边际化是一种受社会、经济、政治和环境等因素综合驱动作用的过程，一种在现有的土地利用和社会-经济结构条件下，农地变得不再具有经济生产能力的过程。在农地边际化过程中，农户会有不同的行为响应，从而导致区域土地利用在“集约度、播种面积、用途转移与土地经营制度”等方面发生重大变化；农地利用的“边际收益指标”、“集约度指标”与“播种面积指标”是诊断农地边际化的三大指标。一般而言，如果该农地利用的“边际收益”为负，且在随后的土地利用过程中出现了“集约度下降、播种面积缩小，甚至弃耕撂荒”等变化特征，可以初步判断该农地利用出现了边际化现象。但不同类型农地边际化，其诊断标准也有差异。

The Character and Diagnostic Criterion for Marginisation of the Arable Land

The concept and essence of marginalisation of arable land and marginal land were defined first, then the character of the marginalisation of arable land use was discussed, and finally, the diagnostic criterion was set up in this paper. The most commonly accepted definition of a marginal agricultural situation is one at the margin of economic viability. Agricultural marginalisation could be considered to be a process, driven by a combination of social, economic, political and environmental factors, by which certain areas of farmland cease to be viable under an existing land use and socio-economic structure. A process of agricultural marginalisation with areas of farmland which cease to be viable may produce a number of different responses from farmers. For example, some may attempt to improve viability and combat marginalisation, whereas others may run down or abandon agriculture altogether. These responses will result in some important changes of arable land use in terms of the degree of intensity, the planting area, the conversion of land use, the management system of arable land use and the abandonment of cultivated land. The marginal return, the degree of intensity and the area of planted crops are three main indexes to diagnose the marginalisation of arable land use. Generally speaking, if the marginal income is negative in the progress of arable land use with such characters as “decline in the degree of intensity and in the planted area, or even the abandonment of arable land”, we can judge that there are marginalisation phenomena in the progress in the land use. However, different kinds of marginalistion of arable land use have different diagnostic criteria.